Department of Stomatology, Third Hospital of Hebei Medical University, ShiJiaZhuang, China.
Int J Oral Maxillofac Implants. 2009 Sep-Oct;24(5):800-7.
This study presents a new rat oral implant model for assessing histologic changes in the mechanical environment surrounding loaded and unloaded dental implants.
The maxillary left first molar from retired breeder rats was extracted, and the site was allowed to heal for 1 month. A titanium miniscrew implant was then placed into the site and allowed to heal for 21 days. The mandibular left first molars in one group of rats were extracted to create an unloaded condition; in a second group of rats the mandibular left first molars were left in occlusion with the opposing screw head to simulate loading. Radiographs were taken on the day of placement and again at 7 days, 14 days, and 21 days after placement and were used to estimate the bone-implant contact ratio. The rats were sacrificed after 21 days. Peri-implant tissue samples from day 21 were processed for histology and immunohistochemistry with antibodies to osteocalcin and matrix metalloproteinase 13 (MMP-13). Two-dimensional finite element models were created from images of the histologic sections and immunohistochemical samples to observe tissue changes.
Areas of high shear stress adjacent to the helical threads of loaded implants were associated with osteocalcin localization and bone formation but only minimal localization of MMP-13. Bone adjacent to unloaded implants showed fibrous tissue and extensive MMP-13 localization surrounding the apical two-thirds of each implant. These results agree with estimated bone-implant contact ratios, which showed a steady decrease in contact ratio for the unloaded implant group but a significantly higher contact ratio in the loaded group between 14 and 21 days.
The rat oral implant model is useful for studies of the mechanical and physiologic environment affecting osseointegration in loaded and unloaded implants.
本研究建立了一种新的大鼠口腔种植模型，用于评估负载和未负载牙种植体周围机械环境的组织学变化。
从退役繁殖大鼠的上颌左侧第一磨牙中提取，并允许该部位愈合 1 个月。然后将钛制微型螺钉种植体置于该部位，愈合 21 天。一组大鼠的下颌左侧第一磨牙被拔出以形成非负载状态；在第二组大鼠中，下颌左侧第一磨牙与对侧螺丝头保持咬合以模拟负载。在植入当天和植入后 7 天、14 天和 21 天拍摄 X 光片，以估计骨-种植体接触比。大鼠在第 21 天被处死。将第 21 天的种植体周围组织样本进行组织学和免疫组织化学处理，使用骨钙素和基质金属蛋白酶 13（MMP-13）的抗体。从组织学切片和免疫组化样本的图像中创建二维有限元模型，以观察组织变化。
负载种植体螺旋螺纹附近的高剪切应力区域与骨钙素定位和骨形成有关，但仅存在最小的 MMP-13 定位。未负载种植体周围的骨显示纤维组织和广泛的 MMP-13 定位，围绕每个种植体的根尖三分之二。这些结果与估计的骨-种植体接触比一致，未负载种植体组的接触比持续下降，但负载组在 14 天至 21 天之间的接触比显著更高。
大鼠口腔种植模型可用于研究影响负载和未负载种植体中骨整合的机械和生理环境。
